One form of plug connection for conduits and more particularly for connecting washing fluid conduits in a motor vehicle comprises a plug receiving means in the form of a socket-like member for receiving a connecting plug portion, for example in the form of a connecting stub with a bore therethrough for carrying the fluid flowing through the conduit. The connecting plug portion can be latched in the plug receiving means in a suitable opening therein, and secured therein to withstand forces acting axially thereon. Such a plug connection or coupling is frequently used in present day windshield or window washing systems and headlamp washing systems in motor vehicles.
A disadvantage with the kind of plug connection outlined above is that the latching elements for holding the connecting plug portion in the plug receiving means are usually difficult to handle. It frequently happens that the washing fluid tank, pump and like components are not freely accessible in the motor vehicle in which the system is installed so that the assembly procedure is faced with difficulties, caused by the fact that the structural space available is only limited. Plug connections which are designed to ensure sealing integrity in relation to pressure surges, for example for high-pressure headlamp washing installations, frequently require particularly high assembly and latching forces to fit the connection together. A corresponding application of force is generally required to release such a plug connection.
A further form of plug connection comprises a first coupling portion and a second coupling portion, in conjunction with a further retaining or latching element. The second coupling portion is generally biased by the retaining element as a separate component against an inward edge of the first coupling portion which is generally of a cup-shaped configuration. Pressure noses on the latching element pass through the first coupling portion into openings and engage behind a step on the second coupling portion. In such a unit the latching element is in the form of a flat ring portion and is made for example from spring steel.
A disadvantage with that form of coupling unit is that the latching element is difficult to grip. Therefore, the outside of the latching element generally has a tongue portion to which a tool can be fitted. That tongue portion however frequently results in damage to cables and conduits which might chaff against it. In addition a tool is also required to disengage the latching element.
Finally a further form of coupling for connecting washing fluid conduits is so designed that a C-shaped latching element can be clipped thereon in the assembled condition of the unit. The latching element has pressure noses which pass through the cup-shaped coupling element or plug receiving means. This part of the coupling which is in the form of a ring portion of plastic material can be gripped with the fingers and can be pressed into the coupling and released again by a rotational movement. Such a coupling however suffers from the disadvantage that initially there is no resistance to insertion movement when the parts of the coupling are being fitted into each other in the insertion direction and the arrangement does not provide for an audible indication that the connection has adopted the latched condition in which the components are fitted together by snap engagement. In addition a further handling procedure is required for fixing the latching element in place. Checking that the parts of the coupling are sealingly fitted into each other is also made more difficult by virtue of the fact that extremely small forces are required for inserting the parts of the coupling into each other.